1. Field of the Invention
The present invention relates in general to a measurement processing apparatus for geometrically measuring an image, and in particular to a measurement processing apparatus for automatically measuring the geometrical data such as the distance between measuring points, the angle formed between two lines connecting measuring points, etc., corresponding to the positional data and the measurement objective of the measuring points set for a medical image or the like displayed on a CRT monitor or the like.
2. Description of the Related Art
Recent years have seen the practical application of CR (Computed Radiography) systems for obtaining radiation images spanning an extremely wide range of radiation exposures, which are used in performing diagnosis at hospitals and other medical facilities. These CR systems utilize stimulable phosphor sheets which store a portion of the radiation energy passing therethrough upon the irradiation thereof with X-rays or other forms of radiation; after which, the stimulable phosphor sheet is irradiated with a visible, infrared, or other excitation light causing a stimulated emission corresponding to the radiation energy stored thereon to be emitted. According to these CR systems, a stimulable phosphor sheet on which the radiation-image data of a target subject, such as a human body, has been stored is scanned with an excitation light and a stimulated emission is caused to be emitted thereby, said stimulated emission is photoelectrically read out by a photomultiplier and obtained as an image signal, and a radiation image corresponding to the obtained image signal is output to film (a photosensitive material), or the display screen of a CRT monitor or the like as a visible-image (refer to, for example, Japanese Unexamined Patent Publication Nos. 55(1980)-12429, 56(1981)-11395, 55(1980)-163472, 56(1981)-104645, 55(1980)-116340, granted to the inventors of the present invention).
Incidentally, in orthopedic surgery and the like, among medical fields, the negative film from which a radiation image was output is employed not only for observation and photographing. For example, as described in the book “A Guide to X-ray Image Measurement in Orthopedic Surgery” by Kazuo Hiroshima and Sakuo Komenobe, Kanehara Press, radiation images are also used for the purpose of measuring geometrical data as in the case of scoliotic curvature (using the Cobb method, the Ferguson method or the like), the Kyphotic index, the ulnar deviation, the radial rotation, etc., wherein an operator actually marks by use of a red pencil or the like the measuring points on a radiation image that has been output to film, and manually measures, using a measuring instrument such as a ruler, a protractor and the like, the distance between the marked measuring points, the angle formed between two straight lines (intersecting lines) connecting measuring points, etc.; based on the measured distance, etc., aforementioned curvature, etc. is computationally obtained, the ratio of the distance between the measuring points is obtained, the area of a desired polygonal region is obtained, etc., and a geometrical measurement (analysis) of the radiation image is performed.
On the other hand, because a radiation image obtained by a CR system is represented by a digital image signal as described above, it becomes possible to automatically obtain the curvature, etc., by displaying the radiation image on the display screen of a CRT monitor or other image display apparatus and then specifying measuring points on this displayed screen, and prerecording the measurement objectives (aforementioned curvature, etc.) and measurement method (aforementioned curvature computation method, etc.), the process of measuring the geometrical data of a radiation image can be automated, whereby the burden of measuring on a measurer, such as a doctor, a radiation technician and the like, can be reduced appreciably.
However, even though it can be said that automatic measuring of the geometrical data of a radiation image becomes possible, the setting of the measuring points on the display screen still depends on a manual input by the operator.
On the other hand, there is a plurality of possible measurement objectives, such as the curvature, the Kyphotic index, the ulnar deviation, etc. described above, and because the positions of the measuring points that must be set for each measurement objective differ, in actuality, it is practicably impossible to memorize the positions that the measuring points should be set at for each of the entirety of measurement objectives.
Further, for cases in which an algorithm for automatically measuring the distance or angle is prerecorded and the curvature or the like is to be automatically derived, although the measuring points must be set according to a predetermined setting order, in actuality, it is practicably impossible to memorize the setting order for each of the entirety of measurement objectives.
Accordingly, when the geometrical data of an image is to be measured, it is necessary to set the measuring points while consulting a manual containing the measurement method, the setting order of the measuring points, etc., and there is a problem in that the efficiency of the measurement and the diagnosis is not always good.